With all those who are producing barrels and bolts for this cartridge are there any standards to go by. Are all the bolts made to the same spec, feed ramps shaped the same , gas port same diameter. Would like to think if  you purchase a 6.8 complete upper from X and the bolt fails that you could use a bolt from Y manufacturer as a replacement and then check for head space. It may not be a big thing for some but it could be  issue at some point down the road.

Try this thread:

6.8 SPC Info

mongo001:
I reviewed the thread you listed in your post, and also the FAQ, did not find anything that addresses my question on what specs are adhered to for the 6.8mm bolts and barrels. Most every thing I have seen on this has to do with ammo and mag issues. I realize it is still early in the game for this cartridge, but I have not seen any thing so far as to those producing 6.8 specific parts are using the same specs. So at this point I have to think it will take a major AR15 manufacturer to standardize these parts.

Didn't know if you saw the thread or not.

Anyway, rumor has it that it may be TOO LATE for the 6.8.  If the .mil has dropped the 6.8, I highly doubt that mags and ammo will as readily available as some had hoped.  I'm sure you will be able to find the stuff, but you may have to work for it.

IMO, there are probably alot of insider reasons why the dates for mags and ammo to be introduced to the public keeps getting pushed farther and farther back.